In a turbine booster system, intake air pressure release is an important issue. During turbine operation, the turbine drives a compressor to form high pressure air which is channeled through an intake passage to pass through a throttle to enter a manifold of an engine. The throttle (also called accelerator) is controlled by a spring. The throttle is closed when the accelerator not is being stepped by a driver. The high pressure air from the turbine is trapped in the intake passage in front of the throttle. When a pedal of the accelerator is stepped by the driver, an accelerator wire draws the throttle spring to open the throttle to allow the high pressure air to enter the engine. When the turbine is in high speed operation and closed abruptly (such as stopping fuel supply by releasing the throttle to perform deceleration or shifting), the pressure between the compressor outlet and throttle increases tremendously and instantly. As the exit pressure of the turbine has no way to escape, it is accumulated in front of the throttle and forms a great instantaneous pressure on the bearing and results in drastic wearing. The compressor also could be damaged, and the main shaft could even be broken. The accumulated pressure has to be released properly. This has to rely on a pressure release process.
The common approach adopted in the conventional technique is bridging the throttle and compressor outlet with an intake pressure release valve. The intake pressure release valve includes at least one spring, a membrane and a bypass channel. The intake pressure release valve has one end to receive boosted outlet pressure of the turbine and the other end connecting to a vacuum duct controlled by the manifold vacuum. When the accelerator is stepped and the throttle is opened, a positive pressure is formed in the vacuum duct to push the intake pressure release valve in a direction such that the spring pushes the membrane to close the bypass channel, the boosted pressure fully enters the engine. When the accelerator is released, the throttle is closed, and the vacuum duct become a negative pressure instantly to attract the membrane, and to bypass the pressure in front of the throttle. The aforesaid structure still has problems, such as vacuum establishing speed in the vacuum duct is too slow. A delay occurs to the reaction speed of the membrane of the intake pressure release valve. And the pressure in the compressor generates vibration in the intake passage and produces noise. On the other hand, if the spring of the intake pressure release valve is not properly chosen, the elasticity coefficient (K value) of the spring is too big, then the negative pressure in the vacuum duct cannot produce enough absorption and pressure release cannot be accomplished. Turbine damage could occur, or pressure release deficiency takes places and results in noise generation in the intake passage.